(1) Technical Field
The present invention relates to a hand tool and a method for using a hand tool for tightening and loosening various styles of locknuts, including locknuts that are used to secure conduit fittings to electrical junction boxes.
(2) Discussion
As depicted in FIG. 1, when wiring residential and commercial structures, it is common to encounter electrical junction boxes 10 and various conduit fittings 12 that interface with them. Although these conduit fittings 12 are designed in differing ways and serve varying purposes, many incorporate external threads as a means to secure them to the electrical junction boxes 10. These threaded conduit fittings 12 are commonly attached to electrical junction boxes 10 by placing the threaded portion of the conduit fitting 12 through a hole 14 in the electrical junction box 10 that was created by removing one of the boxes' knockouts. A locknut 16 is then screwed onto the exposed thread of the conduit fitting 12. Once the locknut 16 is screwed onto the threaded portion of the conduit fitting 12, some means of tightening the locknut 16 must be utilized in order to firmly secure the conduit fitting 16 to the electrical junction box 10.
These locknuts 16 come in a wide variety of shapes and sizes; however, certain design features make them a unique and difficult fastener to apply. First, their cross-section is usually very thin compared to their diameter. This feature makes them difficult to grasp with conventional tools. Second, because of their thin cross-section, they usually have protrusions or lugs extending from their outer diameter to make them easier to tighten or loosen. However, these lugs make it difficult for conventional tools to be applied to the locknut 16 in order to tighten or loosen it. Third, many styles of these locknuts 16 are produced by a stamping process which leaves rounded surfaces on the locknut 16 and protruding lugs, thus making it even harder to obtain a good grip on the locknut 16. Fourth, the confines of electrical junction boxes 10 can become quite cramped for space once the various conduit fittings 12 and their corresponding wire bundles have been inserted. It can become extremely difficult to acquire access for manipulating the locknuts 16 under these conditions.
Heretofore locknuts 16 have been tightened and loosened utilizing hand tools such as pliers, screwdrivers, and wrenches. Most often the particular type of pliers known as CHANNELLOCK® pliers is used. The use of conventional hand tools and CHANNELLOCK® pliers in particular, to tighten and loosen the locknut 16 is problematic. This procedure often results in stripping the projections from the exterior of the locknut 16 which renders the locknut 16 difficult to remove. A related problem involves slippage between the CHANNELLOCK® pliers and the locknut 16 which can lead to damage to parts and equipment and injury to the operator. A cylindrical tool with cylindrical opening has been attempted in U.S. Pat. No. 6,321,625 titled Wrench for Myers Nut, where the cylinder opening of the tool is matched to the dimensions of the cylinder. However, this tool has several drawbacks including the requirement of a number of cylinders for the different size locknuts, the wrench is too large to fit into many tight confined spaces, and the wires cannot be in the fitting when the wrench is used. Another tool available for tightening locknuts is a spanner wrench that has only one jaw and one handle. However, the disadvantage with this tool is that the tool only connects with one lug and one side of lug or protrusion. This again can result in slippage and damage to the locknut 16 and other parts.
There is a need for a hand tool that has: 1) a unique profile shape cut into each jaw member of the hand tool enabling the jaw members to grip and securely hold a wide variety of shapes and sizes of conduit fitting locknuts, therefore, one hand tool can be used to manipulate all locknuts whose diameters fit within the range of opening of the two jaw members; 2) a thin cross-section of both the handles and their attached or integral jaw members enhance the user's ability to utilize the hand tool in confined spaces; 3) the shape of handles that allows both right-handed and left-handed persons to utilize the tool equivalently; 4) the profile shape cut into each jaw member in combination with the shape and thin cross-section of the handles that allows the user to tighten or loosen locknuts regardless of which way the pivot axis of the hand tool is oriented with respect to the axis of rotation of the locknut; and 5) jaw members that can be presented to the locknut perpendicular to the axis of rotation of the locknut and surround it, so that the hand tool can be used to tighten and loosen locknuts even when wires have already been passed through a conduit fitting.